Contractible boring type cutting head for continuous mining machine



Dec. 4, 1956 B. F. TRACY CONTRACTIBLE BORING TYPE comm; HEAD FOR CONTINUOUS MINING MACHINE 5 Sheets-Sheet 1 Filed May 3, 1955 INVENTOR. Beryamln F Tracy BY 77 ATTORNEY Dec. 4, 1956 Filed may 3, 1955 B. F. TRACY CONTRACTIBLE BORING TYPE CUTTING HEAD FOR CONTINUOUS MINING MACHINE 5 Sheets-Sheet 2 INVENTOR.

Benjamin F Tracy ATTORNEY Dec 4, 1956 B. F. TRACY CONTRACTIBLE BORING TYPE cu'rmc HEAD FOR commuous MINING mcnms 5 Sheet's-Sheet 5 Filed lay a, 1955 Fig. 3

CONTRACTIBLE BORING, TYPE CUTTING HEAD FOR CONTINUOUS MINING MACHINE Benjamin F. Tracy, Point Pleasant, W. Va., assignor to Goodman Manufacturing Company, Chicago, 111., a

corporation of Illinois Application May s, 1955, Serial No. 505,701

9 Claims. (Cl. 262-7) This invention relates to improvements in contractible boring arm assemblies for continuous mining machines. It is particularly adaptable to small bore machines where the space for contracting the boring arms is extremely limited.

Since many mine roof conditions require 'timbering behind the mining machine, and quite close to the face, there must be some provision for collapsing the cutting elements when the machine is backed into the'timbered part 'of the entry. And, as the. size of timbers used to support the roof remains practically constant regardless of the height of the seam being mined, the amount of collapsibility required .in a small bore continuous miner will be as great as that required in a larger bore machine. Therefore, the percentage of collapsibility required will increase as the'cutting height of the continuous miner is decreased. 'For example, if a continuous miner with a cutting height of 72 inches required 18 inches or 25% collapsibility, asimilar machine designed with a 45 inch cutting height would require .18 inches or.about 40% collapsibility. In the larger machines, the problem, of providing for a -great am ount of collapsibility .is most easily solvedby hinging the boring arms to fold forwardly asshown in the co-pending application of FrankCartlidge,-1Serial No. 431,454, filed May .21, 1954. In this type of hinged arm structure, the torsional strain imposed on each arm by the action of the cutter bits is transmitted directly to the hinge joint, which, in order. to resist. the extremely heavy loads, must be very large and sturdily constructed. Placing large hinge joints on the periphery of the hub of the rotating head increases the minimum diameter of the non-collapsible hub portion and, therefore, decreases the amount of collapsibility which may be built into such a boring head.

A primary object of this. invention is the provision of a hinged boring arm structure in which the large joint is relieved of the torque loads between the hub and the boring arm, allowing said joint tobe, made smaller, thereby permitting more collapsibility to be built into said structure. I 1

Another object. is to provide a hinged boring arm structure in which the central'burster cone is fixed to the folding arm so that saidarm may fold into the central position normally occupied by said burster cone.

Another object is to provide a hinged boringarrh structure in. which the hinge. joint of the boring arm is located on-thei'side" of the axis of the rotatable hub opposite that side occupied by the major portion of the boring arm. 1

Another object 'is to provide a hinged boring armto make the initial entry into the mine face.

is now considered to be the best mode of applying the:

principles thereof.

In the drawings: Figure 1 is a front view of a boring head for a continuous mining machine, constructed in accordancewith the present invention and showing the hinged. boring arm in fully extended position; I

Figure 2 is a part sectional view of the boring head shown in Figure 1 taken generally along the line 22;

Figure 3 is a part sectional view similar to Figure 2,

but with the hinged armflin forwardly collapsed position.

Referring now to the drawings, Figure 1 shows a rotatable boring head 10 having acentral hub portion 11. The forward portion of hub,11 is formed in a generally 9 U-shaped section having parallel guides or side walls 12, 12 connected at oneend by an end wall 13;. A pair of short diametricallyopposed cutter arms 14, 14- extend radially from the hub 11 at right angles to the side walls 1 12, 12. A pivot pin'16 extends transversely between the side walls 12, 12 adjacent. the end 'wall 13; and pivotally supports a long cutter arm 17 extending radially across the axis of the hub 11 at right angles to the. cutter arms 14, 14. The cutter arms14, 14 and 17 have mount ed to them, by means not shown, forwardly projecting brackets 18, 1 8 and 19, respectively. Each of saidbrackets has welded to its forward extremity a plurality of bit holders 21 in which are secured cutter. bits 22.

the rotating head 10, while the bits 22 carried by the brackets 18, 18 on the arms 14, 14 cut an intermediate kerf 24 between the outer kerf .23 and the axis of rotation of the head. The arm 17 also carries a forwardly projecting burster cone 26 provided with a pilot bit 27 g The cone 26 is designed to enterthe bore produced by the pilot bit 27 and to burst the inner annular core formed within" the kerf 24. The cone 26 is fixed to the arm 17 so as to be coaxial with the hub 11 when the arm 17 is in its the hub 11 provides clearance for the boss 34 when the arm 17 is in the extended position. t

One of the principal features of the present invention is that the arm 17 is closely fitted for hinged movement between the side walls 12, 12 of the hub 11. Thus, all torsional and bending strains which may be imposed on the arm 17 by the action-of the cutter bits is trans-' mitted directly to the hub 11 through the side ,walls 12, 12. This method of construction relieves the hinged joint on arm 17 of all torque loads, permitting said joint to be made much smaller yet relatively stronger than the constructions used in the prior art.

In operation of the machine, it will be understood that the hinged arm 17 is normally extended'in a generally perpendicular relation to the axis of rotation of the boring head so as to cut the outer kerf 23 at maximum diameter as shown in Figure 2. When it is desired to fold of swing the hinged arm forwardly to reduce the overall diameter of the boring head, the central shaft shown) ure 3. It will be apparent that the burster cone 26, being integral with the arm 17, cannot interfere with'the for- Ce Patented Dec.4, 1956 3 ward swinging movement 'of said arm across the rotational axis of the boring head. The added freedom of movement thus made available to the arm 17 permits a greater percentage of collapsibility to be designed into the boring head making such designs practical for small bore continuous mining machines.

The pin and slot connection between the actuating shaft 31 and the arm 17 eliminates a separate connecting link between these parts and greatly simplifies the construction, making it less expensive to manufacture and reducing maintenance operations in the field.

Rearward movement of the actuating shaft 31 extends the arm 17 into the cutting position shown in Figure 2. Stop means are provided within the hub 11 for limiting the rearward hinged movement of the arm 17 relative to the hub 11, said stop means consisting of machined faces 38, 38 on either side of the recess 37 which contact the rear-face 36 of the arm 17.

Although I have shown and described a certain embodiment of my invention, I do not wish to be understood as limiting myself to the exact construction shown and described, but that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. A boring type cutting head for a continuous mining machine of the type having a rotatable hub, an arm supported by the hub, and a cutter bit bracket projecting forwardly from the outer end of the arm; the improvemerit comprising: a hinge joint connecting the inner end of 'the arm to the side of the hub opposite the outer end of said arm; said hinge joint including a hinge pin mounted on an extension of the hub which is offset from the hub in a direction opposite the outer end of the arm.

2. A boring type cutting head for a continuous mining machine of the type having a rotatable hub, an arm supported by the hub, and a cutter bit bracket projecting forwardly from the outer end of the arm; the improvement comprising: a transverse hinge joint connecting the inner end of the arm to the side of the hub opposite the outer end of said arm; and guide means on the hub to laterally support the arm intermediate the ends thereof, said hinge joint including'an extension of the hub radially offset from said hub in a direction opposite the. outer end of the arm and carrying a hinge pin'onto which said inner end ofsaid arm is pivoted/ 3. A boring type cutting head for a continuous mining machine of the type having a rotatable hub, an arm supported by the hub, and a cutter bit bracket projecting forwardly from the outer end of the arm; the improvement comprising: a hinge joint connecting the inner end of the arm to the side of the hub opposite the outer end of said arm; guide means on the hub to laterally support the arm intermediate the ends thereof; and actuating means to swing the arm forwardly and inwardly about the hinge joint; said hinge joint including a hinge pin mounted on an extension of the hub which is offset from the hub in a direction opposite the outer end of the arm.

4. A boring type cutting head for a continuous mining machine of the type having a rotatable hub, an arm supported :by the hub, and a cutter bit bracket projecting forwardly from the outer end of the arm; the improvement comprising: a hinge joint connecting the inner end of the farm to an extension of the hub offset from the hub in a direction opposite the outer end of said arm; and sidewalls on the hub in sliding engagement with the sides of the arm effective to transmit torque between the huband the arm independently of the hinge joint.

5. A boring type cutting head for a continuous mining machine of the type having a rotatable hub, an arm supported by the hub, and a cutter bit bracket projecting forwardly from the outer end of the arm; the improvement comprising: a joint including a hinge pin connecting the innerend of the arm to an extension of the hub offset from the hub in a direction opposite the outer end of said arm; sidewalls on the hub in sliding engagement with the sides of the arm effective to transmit torque between the hub and the arm independently of the hinge joint; and actuating means to swing the arm forwardly and inwardly about the hinge joint.

6. A boring type cutting head for a continuous mining machine of the type having a rotatable hub, an arm supported by the hub, and a cutter bit bracket projecting forwardly from the outer end of the arm; the improvement comprising: a hinge joint connecting the inner end of the arm to a radially offset extension of the hub diametrically opposite the outer end of said arm; sidewalls on the hub in sliding engagement with the sides of the arm effective to transmit torque between the hub and the arm independently of the hinge joint; a reciprocable shaft coaxial with the hub; a 'pin and slot connection between the arm and the forward end of the shaft; said shaft being shiftable to fold said arm forwardly and inwardly about said hinge joint.

7. A boring type cutting head for a continuous mining machine of the type having a rotatable hub, an arm supported by the hub, and a cutter bit bracket projecting forwardly from the outer end of the arm; the improvement comprising: a hinge joint connecting the inner end of the arm to the side of the hub opposite the outer end of said arm; sidewalls on the hub in sliding engagement with the sides of the arm effective to transmit torque between the hub and the arm independently of the hinge joint; a forwardly projecting burster cone attached to the front face of the arm and positioned thereon so as to be coaxial with the hub when the arm is in fully extended cutting position; and actuating means to swing the arm forwardly and inwardly about the hinge joint.

8. A boring type cutting head for a continuous mining machine of the type having a rotatable hub, an arm supported by the hub, and a cutter bit bracket projecting forwardly from the outer end of the arm; the improvement comprising: a hinge joint connecting the inner end of the arm to the side of the hub opposite the outer end of said arm; sidewalls on the hub in sliding engagement with the sides of the arm effective to transmit torque between the hub and the arm independently of the hinge joint; a forwardly projecting burster cone attached to the front face of thearm and positioned thereon soas to be coaxial with the hub when the arm is in fully extended cutting position; a reciprocable shaft coaxial with the hub; a pin and slot connection between the arm and the forward end of the shaft; said shaft being shiftable to fold said arm forwardly and inwardly about said hinge joint.

9. A boring type cutting head for a continuous mining machine of the type having a rotatable hub, an arm supported by the hub, and a cutter bit bracket projecting forwardly from the outer end of the arm; the improvement comprising: a hinge joint connecting the inner end of the arm to the side of the hub opposite the outer end of said arm; sidewalls on the hub in sliding engagement with the sides of the arm etfective to transmit torque between the hub and the arm independently of the hinge joint; a forwardly projecting burster cone attached to the front face of the arm and positioned thereon so as to be coaxial with the hub when the arm is in fully extended cutting position; a reciprocable shaft coaxial with the hub; a pin and slot connection between the arm and the forward end of the shaft; said shaft being shiftable to fold said arm forwardly'and inwardly about said hinge joint; and stop means on the hub to limit rearward swinging movement of the arm about the hinge joint.

References Cited in the file of this patent UNITED STATES PATENTS 

